Vibratory hammer drill

ABSTRACT

This invention relates to a fluid-actuated percussion tool for applying repeated blows to a drill bit in the drilling of wells. The tool is connected to the lower end of the drill string just above the bit. The tool includes a hammer slideably mounted within the housing and an axially hollow anvil fitted within the housing below the lower end of the hammer. The hammer has a bore extending from the upper end which seats over a center guide tube which is in communication with the exterior of the tool. The lower end of the hammer is closed and forms a valve which seats with the upper end of the anvil. Differential areas and changing pressures on the hammer cause it to reciprocate and repeatedly strike the anvil.

United States Patent 72] Inventor Renic P. Vincent, deceased late of Tulsa, Okla. by Meta Luella Vincent, administratrix 21 Appl. No. 17,409 [22] Filed Mar. 9, 1970 [45] Patented Dec. 28, 1971 [73] Assignee Amoco Production Company Tulsa, Okla.

[54] VIBRATORY HAMMER DRILL 8 Claims, 3 Drawing Figs.

52 U.S.Cl 173/17, 173/73 [51] Int. Cl B23g 5/00, E21c 7/00 [50] Field of Search 173/16,17, 73, 80

[56] References Cited UNlT ED STATES PATENTS 2,979,033 4/1961 Bassinger 173/73 2,837,317 6/1958 Hulshizer 173/17 Primary Examiner-David H. Brown Attorneys-Paul F. Hawley and John D. Gassett ABSTRACT: This invention relates to a fluid-actuated percussion tool for applying repeated blows to a drill bit in the drilling of wells. The tool is connected to the lower end of the drill string just above the bit, The tool includes a hammer slideably mounted within the housing and an axially hollow anvil fitted within the housing below the lower end of the hammer. The hammer has a bore extending from the upper end which seats over a center guide tube which is in communication with the exterior of the tool. The lower end of the hammer is closed and forms a valve which seats with the upper end of the anvil. Differential areas and changing pressures on the, hammer cause it to reciprocate and repeatedly strike the anvil.

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1 VIBRATORYIIAMMER DRILL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to fluid-actuated tools for applying repeated percussive blows to a drill system in the drilling of oil and gas wells and the like. In particular, the invention is related to percussion motors for incorporation in drill strings, causing drill bits to vibrate or oscillate axially at the same time they are being rotated for the drilling of such wells.

2. Setting of the Invention A number of designs of percussion motors for drilling boreholes in the earth have been suggested and used in the past; these include those described in US. Pat. Nos. 3,327,790 and 3,464,505. The percussion motor is mounted at the lower end of the drill string and in turn is connected to a suitable drilling bit. The high-pressure fluid circulating through the drill string, percussive motor and bit causes the bit to oscillate percussively against the formation and thus producing a major part of the drilling effect. The drill string is continually rotated, both to produce a further drilling eflect and to minimize deviation in the direction of the hole. The compressed fluid from the percussion motor normally flows out through the bit and up the annulus between the walls of the hole and the drill string to the surface, carrying formation cuttings and well fluids with it.

BRIEF DESCRIPTION OF THE INVENTION The invention includes a housing having an axially hollow anvil mounted in the lower end. A bit is attached to the anvil. A center guide tube is mounted in the upper portion of the housing and is in fluid communication with the exterior of the bit. A hammer having a bore part way through is sealingly and slideably mounted about the center guide tube above the anvil. The lower end of the hammer mates with the bore of the anvil to form a valve when the hammer is in its lower position. The hammer is of smaller diameter than the inside of the housing so that there is a flow space or flow annulus therebetween. Pressure drop through the flow annulus, pressure buildups and reductions, and differential areas cause the hammer to oscillate.

DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a cross section of the tool.

FIG. 2 is a cross section of a portion of the tool showing the hammer and anvil in their lowermost position.

FIG. 3 is a sectional view along the line 3--3 of FIG. 1 and shows a modification of the configuration of the hammer of FIG. 1.

Attention is directed to the drawing in which a housing 10 is adapted to be connected at its upper end by threads, not shown, to the lower end of string of drill pipe, not shown. Mounted within housing 10 is a center guide tube 14 which has an opening 16 through the wall of housing 10 to the space exterior ofthe housing. The lower end 18 of guide tube 14 is open. Just above the lower end of the guide tube are ports 20.

Mounted about the lower end of guide tube 14 is hammer 22 which has a bore 42 which extends only part way therethrough. Seals 24 are provided between bore 42 of the hammer and the guide tube. The seals 24 are ordinarily above ports 20. As will be seen, only when the tool is in its extended position are the seals below the ports.

Mounted just below the hammer is anvil 26. Anvil 26 has a bore 28 which extends through the anvil. A bit 30 is attached to the lower end of anvil 26. The anvil is held in place by splines 32 which are attached by bolts 34 or other means to the anvil body itself. Splines 32 are mounted in slots 36 in the wall of the lower end of housing 10. Seals 38 are provided between anvil 26 and the inner wall of housing 10 above slots 36.

The upper end of hammer 22 has an area A. which is exposed to a pressure P ln the upper end of housing 10. There is an annular flow space 40 between hammer 22 and the interior of housing 10. The flow space can be in the form of grooves 41 or flutes, as shown in FIG. 3, so that guiding is provided between the hammer and case. Also, the grooves can be spiraled to cause the hammer to rotate slightly and equalize wear between the hammer and mating parts. The lower end of bore 42 of hammer 22 has an area A The pressure in bore 42 below seals 24 is P;,.

The hammer 22 seats with anvil 26 by a finger valve 44 which extends into the bore 28 of the anvil. The lower end of the hammer also has grooves 46 therein. The pressure between the hammer and the anvil in grooves 46 is referred to as P The fluid pressure within bore 28 of the anvil is v identified as P;. The lower end of hammer 22 has a first area A, and a second area A,. Area A, is that area of the lower side of hammer 22 in fluid communication with fluid having pressure P Area A, is the area of the lower end of finger valve 44 which is in fluid communication of pressure P In operation the apparatus of FIG. 1 is connected into a drill string and drilling fluid, which is preferably a gas, is directed downwardly through the tool. At times the downward force on hammer 22 exceeds the upper force and at other times the upward force exceeds the downward force. Thus reciprocation is effected. The downward force, excluding the weight of the hammer, is given by equation I:

l. P A +P A The upward force is given by equation 2:

The areas A,, A A and A and pressures P, and P ordinarily remain substantially constant during operations of the tool. However, P and P vary. It is this variation of these pressures which causes the upward force to exceed the downward force. When the hammer 22 is in its upper position away from anvil 26, there is a rather large pressure loss AP through the flow annulus 40. Thus at this time P, is considerably less than P,. However, when finger valve 44 is inserted into the bore 28 of anvil 26 the flow is substantially stopped. Then the pressure starts to equalize in the flow annulus 40 so that P, is essentially equal to P Thus when P, equals P, and with P, ordinarily being greater than P then the balance of force is upward inasmuch as A,+A ==A +A P is ordinarily greater than F; because P, is upstream of the pressure P and in a flowing stream, the upstream point is always at a higher pressure than the downstream point.

The hammer 22 rises until finger valve 44 permits a substan tial volume of fluid to flow downward through bore 28 through anvil 26. When this occurs there exists a large AP through the flow annulus 40 so that P again becomes much less than P,. At this point the balance of force is downward; thus the hammer 22 is driven down to impact again against the top of anvil 26.

Sometimes it is desired to circulate fluid down the drill string and back up the annulus to the surface at times when it may not be desirable to operate the percussion tool. This is readily accomplished with my invention. All one has to do is pick up on the drill string and at that time the splines 32 of the anvil slide down into contact with shoulders 35 at the lower end of slots 36 of housing 10. As shown in FIG. 2 hammer 22 follows the anvil down to a position where seals 24 are below port 20 of center tube guide 14. Then the circulation point is down the tubing, through the interior of housing 10 above hammer 22, through ports 20, up center tube 14 and back through the annulus between the drill pipe and borehole wall to the surface.

When using a noncompressible fluid such as water as the drilling fluid, it is desired to modify the valve part of hammer 22 and anvil 26. One modification is shown in FIG. 2. The finger valve has been removed. There the flow of fluid is shut off by contact of the hammer with the anvil upon impact. Grooves 46 are provided in the lower end of hammer 22 but are not in communication with bore 28. These grooves 46 are indicated in the drawing as being radial. Such illustrated grooves start at the outer periphery and terminate at a point which is at a greater distance from the longitudinal center of the hammer 22 than the radius of bore 28 of the anvil 26. The area of grooves 46 is selected so that when the hammer is seated against the top of anvil 26, the upward force on the hammer exceeds the downward force. The hammer will reciprocate in the manner described above.

While the above figures have been described with a great amount of detail, it is possible to make other variations without departing from the spirit and scope of the invention.

It is claimed:

1, A fluid percussion drill which comprises:

an elongated housing member having a bore therethrough inserted in the lower end of said housing member;

means holding said anvil member to said housing member;

a center guide tube supported from said housing member in the upper part thereof above said anvil member;

a hammer having a bore only part way through with only one open end, said hammer placed above said anvil member, said center guide tube being inserted into said bore of said hammer, there being a flow channel within said housing member from above said hammer to below said hammer;

said hammer including means at its lower end for mating with the upper end of said anvil member to effect stoppage of fluid flow therethrough.

2. A drill as defined in claim 1 in which said flow channel is a plurality of grooves in the outer wall of same hammer.

3. A drill as defined in claim 1 in which said flow channel is from between the outer wall of said hammer and the inner wall of said housing member.

4. A drill as defined in claim 1 in which said center guide tube is in fluid communication with the exterior of said housing member.

5. A drill as defined in claim 4 including a sealing means between said bore of said hammer and the outer wall of said center guide tube and a port in the wall of said center guide tube below said sealing means when said hammer is in operating position, and when said hammer and anvil member are in their lowermost position, said port is above said hammer.

6. A drill as defined in claim 5 in which the bottom side of said hammer has radially extending grooves starting at the outer periphery and terminating at a point which is at a greater distance from the longitudinal center of said hammer than the radius of the bore of said anvil member.

7. A drill as defined in claim 5 in which the means at the lower end of said hammer for mating with the upper end of said anvil to efiect stoppage of flow therethrough includes a finger valve on the lower end of said hammer for insertion into the bore of said anvil member to stop the flow of fluid therethrough.

8. A drill as defined in claim 7 in which the bore of said anvil member has a smaller cross-sectional area than the bore of said hammer. 

1. A fluid percussion drill which comprises: an elongated housing member having a bore therethrough inserted in the lower end of said housing member; means holding said anvil member to said housing member; a center guide tube supported from said housing member in the upper part thereof above said anvil member; a hammer having a bore only part way through with only one open end, said hammer placed above said anvil member, said center guide tube being inserted into said bore of said hammer, there being a flow channel within said housing member from above said hammer to below said hammer; said hammer including means at its lower end for mating with the upper end of said anvil member to effect stoppage of fluid flow therethrough.
 2. A drill as defined in claim 1 in which said flow channel is a plurality of grooves in the outer wall of same hammer.
 3. A drill as defined in claim 1 in which said flow channel is from between the outer wall of said hammer and the inner wall of said housing member.
 4. A drill as defined in claim 1 in which said center guide tube is in fluid communication with the exterior of said housing member.
 5. A drill as defined in claim 4 including a sealing means between said bore of said hammer and the outer wall of said center guide tube and a port in the wall of said center guide tube below said sealing means when said hammer is in operating position, and when said hammer and anvil member are in their lowermost position, said port is above said hammer.
 6. A drill as defined in claim 5 in which the bottom side of said hammer has radially extending grooves starting at the outeR periphery and terminating at a point which is at a greater distance from the longitudinal center of said hammer than the radius of the bore of said anvil member.
 7. A drill as defined in claim 5 in which the means at the lower end of said hammer for mating with the upper end of said anvil to effect stoppage of flow therethrough includes a finger valve on the lower end of said hammer for insertion into the bore of said anvil member to stop the flow of fluid therethrough.
 8. A drill as defined in claim 7 in which the bore of said anvil member has a smaller cross-sectional area than the bore of said hammer. 